Known in the art is an apparatus for thermal deburring of parts, comprising an C-shaped frame having a working chamber and a worktable having bottom members for supporting parts, the bottom members alternately sealing a loading hole of the working chamber (cf. U.S. Pat. No. 3,666,252, Cl. 266-2, publ. 1972). This apparatus has powerful hydraulic cylinders with a linkage for retaining the bottom member in the loading hole of the chamber during combustion of a fuel mixture.
The retaining linkages feature a high rigidity, hence high consumption of metal for their manufacture since the linkage members have to take up considerably impulse loads without elastic deformations so as to ensure reliable sealing of the chamber. For the same reason, the prior art apparatus is provided with a rugged and rigid bed.
At the same time, use of the retaining linkages lowers productivity since time is needed for their actuation during retaining and release of the bottom member.
The parts having been treated, the hydraulic actuator acts upon the linkage which lowers the bottom member. The combustion products at high pressure and temperature are discharged through the opening thus defined so as to act directly upon the PTFE seal which would rapidly fall.
Also known in the art is an apparatus for thermal deburring of parts, comprising a cylindrical working chamber having an inlet valve, an outlet valve and a spark plug, a bottom member for closing and opening a loading hole of the chamber having a worktable for supporting parts being treated and mounted for axial movement with respect to the chamber, and an elastic sealing ring for sealing the joint between the bottom member and the chamber (cf. USSR Inventor's Certificate No. 988499, Int.Cl. B 2 K 28/00, publ. 1983).
This apparatus cannot, however, ensure a high enough productivity and reliability in operation since reliable retainment of the bottom member in the chamber is necessary so as to prevent the bottom member from being forced out during filling and ignition of a fuel mixture. In order to accomplish this, the prior art apparatus makes use of a rotatable sleeve defining a bayonet lock with the bottom member, the members of the lock taking-up maximum process forces, i.e. they are acted upon by a force determined by maximum pressure of combustion products of the fuel mixture. The provision of the rotatable sleeve and a drive for its rotation results in a greater metal consumption for manufacture, and repeated loading of the members of the bayonet lock results in their deformations and rapid wear thus lowering reliability of the apparatus. The need to rotate the sleeve after the bottom member has been raised so as to form the bayonet joint and to rotate the sleeve back in the opposite direction for releasing the bottom member after the parts have been treated result in a longer working cycle and limit productivity. In addition, the apparatus is not reliable enough in operation since the direct action of high temperature and pressure of combustion products upon the elastic sealing ring disposed between the working chamber and bottom member is not eliminated.
Sealing the working chamber by means of an elastic sealing ring is not efficient; the ring, which is in direct contact with the fuel mixture is rapidly worn under the action of high temperature and pressure generated by combustion of gas-oxygen mixtures; the ring may also be burnt-through, broken, and the like. All these factors lower reliability and safety of the apparatus in operation while long time intervals needed for retaining and releasing the bottom member lower productivity.